flying bird vs carinate bird

flying bird and carinate bird both are nouns.

As nouns, flying bird and carinate bird are synonyms defined as:

flying bird and carinate bird: birds having keeled breastbones for attachment of flight muscles

Other synonyms of flying bird include carinate.

flying bird (noun)	carinate bird (noun)
birds having keeled breastbones for attachment of flight muscles	birds having keeled breastbones for attachment of flight muscles